Almost three-quarters of British beaches are littered with tiny plastic pellets, according to the results of a coordinated public search. The pellets - each about the size of a lentil - are known colloquially as "nurdles," and while that may sound more like an adorable furry animal, their prevalence is a serious problem.

Nurdles are used each year in the manufacture of plastic products, but during manufacture, transport or use, many are spilled into rivers or oceans or down drains to be washed out to sea. An estimated 53 billion pellets are reckoned to be released annually into the environment of the U.K. alone.

One of the principal sources of primary microplastics - that is to say, small pieces of plastic that aren't from larger items that have broken down over time - in European seas, nurdles are problematic for multiple reasons. They attract and concentrate chemical pollutants such as DDT and PCBs, making them highly toxic to wildlife that ingests them. And, being plastic, they are highly persistent in the environment.

Earlier this month, at least 600 volunteers searched 279 beaches along the British coast as part of the Great Winter Nurdle Hunt, organized by the Scottish environmental charity Fidra in collaboration with a number of other organizations. Seventy-three percent reported finding the plastics, from the Scilly Islands in the southwest to the Scottish archipelago of Shetland. The largest number of individual pellets found was 127,500 on a 325-feet stretch of coastline in Cornwall.

Fidra will be feeding the results into a British government consultation on microbeads and other microplastics, which was announced last December. Microplastics are anywhere from 5 mm in size to just 1 nanometer. Primary microplastics, like the ones manufactured from nurdles, are intentionally manufactured and super-small, primarily used in cosmetics and personal-care products, industrial scrubbers used for abrasive blast cleaning, microfibers used in textile, and pellets used in plastic manufacturing processes. Secondary microplastics are the result of larger pieces of plastic disintegrating over time.

"Simple precautionary measures can help spillages and ensure nurdles don't end up in our environment," said Madeline Berg, the organization's projects officer. "We are asking the U.K. government to ensure best practice is in place along the full plastic supply chain, and any further nurdle pollution is stopped."